I hope, this hasn't been posted too much already and I haven't seen it on the last sites.
I got a 8800gs, which is seen and used by BOINC, and I added aditionally the 8400gs with 256 MB ram, that BOINC might use it also, as I got it lying here.
Drivers etc. are fine ...
If you need the specs of my Serversys:
AMD X4 630
4 GB Ram
8800 320 & 8400 256
780G Chipset.

I know, that the 8400gs isn't the big bang, but if Boinc can use it, why shouldn't it do?

Hey...
Since I plugged a monitorcable to the 8400gs, and marked it as active, the Cudasupport etc. is enabled.. So Boinc is using it now, thanks people.
At last I got a little improvement, for no money @crunching.